The present invention relates to a sealing ring having at least one jacket surface serving as slide surface, such as, in particular, a sealing ring for sealing articulatedly connected pipe ends subjected to high temperature stresses, preferably the exhaust pipes of internal-combustion engines where there are high temperature stresses, the sealing ring comprising pressed together fiber materials, preferably of metal and sliding agents.
For example, in exhaust systems of internal-combustion engines, it is known to articulatedly connect the pipe ends of the exhaust gas manifold and the exhaust gas outlet pipe by means of a pipe coupling system which operates according to the ball and socket principle so as to avoid the transfer of vibrations generated by the engine. The sealing ring placed between the pipe ends is adapted to the outlines of the ball or to the ball socket segments, respectively, and, during operation of the engine, is subjected to sliding and friction stresses which attack at least the jacket surface of the sealing ring.
Pursuant to this slide bearing function, such sealing rings, in a modern design, are composed of pressed together metal fiber materials on the basis of, usually, steel fibers and solid sliding materials, usually graphite. The embedded metal fiber body then forms the skeleton of the sealing ring which is saturated and coated with the sliding material.
Thus, according to DE-OS No. 2,829,333 the reinforcing fiber core is comprised of a suitably folded steel wire fabric which is wound in the circumferential direction of the ring. In this case, however, there exists the danger that the steel wires may break, particularly at the points where the wire fabric is folded, and the wire ends then penetrate the slide coatings covering them so that the wire ends contact the slide faces of the pipes. During stresses from engine operation, seizing phenomena and squeaking noises will then develop at these locations with ever increasing damage from wear and finally the connection becomes untight. To overcome this problem, DE-PS No. 2,845,949 employs individual, relatively long steel fibers arranged preferably in the circumferential direction, or, according to DE-OS No. 3,107,920, a reinforcing metal fiber skeleton of steel wool is used in which the steel fibers have irregular orientations.
In other cases, steel fibers of relatively short length and graphite powders are initially combined into the most homogeneous mixture possible, thus forming, with pressing, a sealing ring of a solid metal fiber felt, with solid lubricants embedded therein and coating the same. Although such measures substantially improve the sealing rings with respect to their susceptibility to wear, this is not the optimum solution for the above-described problem and damage from seizing continues to appear between metal and metal contact points during engine operation.